Two 91's with different power levels

[patpend2000]

My family has owned two 91 FJ80's, one since new the other bought used with 75K. Currently they both have over 200K miles. The one that we bought new has always been slower than the one we bought used.

The used one can easly distance itself from the other. How can I adjust the slower one to have the power of the used one? Valves? Timing?

Kelly

 

[overhanger]

Try swapping the EFI computers. It's a one banana job.

 

[nyk438]

Wouldn't that make the new one as slow as the old one used to be? I know this is normal logic, but just checking since I'm probaly wrong

 

[ginericLC]

I'd check timing first. Maybe the more powerful one is slightly advanced? I'm sure all the other things have been changed out over that period of miles: air cleaner, spark plugs, etc...

It would be interesting to see if a computer swap would change the power. But by unplugging it you should lose the stored codes so maybe it wouldn't?

 

[patpend2000]

swapping computers

The only problem with swapping computers is that one truck is located in CA and the other is located in Montana, so this cannot be done easily. What is the recommended timing setting for a 3FE. How much advance can I get away with?

Would a set of clogged catalytic convertors reduce power that much? If so, how can I determine if they are clogged? BTW, has anyone used the cats from discountconvertor?

Kelly

 

[overhanger]

The used one really did distance itself from the other one then!
7 degrees BTDC is factory timing spec iwth the ECU bypass jumper in place and you might be able to go 3-5 degrees higher without problem, depending on engine condition and the quality of gas you use. As for clogged cats the easiest way to unclog them is to drive Grapevine Hill or some steep grade in the Grand Tetons as fast as you can a few times. In other words, run the engine hard to get it good and hot to burn the crap out of the cats.

 

[cruiserdan]

Um, let me guess........

The Montana Cruiser is the one with less power?


ALTITUDE.............

 

[Hltoppr]

You beat me to it CDan....

Yeah, my 1992 has a heck of a lot more power in Phoenix (1300') than up here in Flagstaff (7000').

-H-

 

[patpend2000]

Nope, the Montana cruiser has MORE power, that's why I'm at a loss, when they were both in CA the power difference was the same as it is now.

As for the grapevine, I can only average about 35-40mph over it. Nothing fast enough to blow the crap out of the cats. I live in the bay area near San Francisco, and I have troubles with the small hills here. Going up the altamont I can only do about 50mph. I nearly get killed.

Kelly

 

[robbie]

Do you know if a HG has been done. Look at the head to see if the oil galley plug is a screw type(not the press in type) If so maybe the PO had the head removed to fix this and at the same time had the head milled. thus creating more power. later robbie

 

[semlin]

How about service histories? Does the from one from new maybe have a clogged air filter? How about the plugs and plug wires. Does one have a newer set? (oem plug leads they are date stamped on the wires). Fuel filter? From my very recent readings, there are those who claim a new fuel pump regulator can make an old 3FE run a lot better even if no apparent symptoms.